1. Field of the Invention
The present invention pertains to the art of dishwashers and, more particularly, to a pressure relief system for a filter chamber portion of a dishwasher pump assembly.
2. Discussion of the Prior Art
In a typical dishwasher, washing fluid is pumped from a sump into upper and lower wash arms such that kitchenware retained on vertically spaced racks within a tub of the dishwasher will be sprayed with the washing fluid for cleaning purposes. The washing fluid is recirculated through operation of a wash pump. Prior to recirculating the washing fluid, the fluid is directed through one or more filters to remove soil from the fluid, with the soil being collected in a chamber. Periodically, the system will be purged in order to drain the chamber of the soil.
Despite the periodic purging of the system, the filter chamber can become prematurely clogged. That is, if a large amount of soil becomes entrained in the washing fluid, the soil can clog a filter screen portion of the filter chamber. In recognition of this problem, manufacturers have developed several systems designed to prevent the filter from becoming clogged. One proposed solution is a backflush system wherein a spray of washing fluid, typically from the lower wash arm, is directed downward onto the filter. The spray of washing fluid passes through the filter, in a direction opposite to a flow of cleansed washing fluid exiting the filter, to wash away soil particles blocking the filter openings.
Another proposed solution includes placing a pressure sensor in the filter chamber. In the event the filter becomes clogged, pressure will begin to rise in the filter chamber. Sensing the rise in pressure, the pressure sensor will trigger a drain operation by activating a drain pump directly connected to the filter chamber to remove all the washing fluid from the filter chamber. While effective at alleviating a clogged filter, operating the drain pump increases an overall noise output by the dishwasher. Today's consumers are demanding quieter appliances. Repeated or excessive operation of the drain pump will not meet the demands of these consumers. In addition, incorporating a pressure sensor into the filter chamber necessarily provides an additional failure point in the system. That is, if the sensor fails, the filter chamber could remain clogged during an entire, or at least a substantial portion of, a wash cycle. If this occurs, dishes will not be properly cleaned and the consumer will feel disappointed in the quality of the product.
Therefore, despite the existence of pressure relief systems in the prior art, there still exists a need for an enhanced pressure relief system for a filter chamber employed in a dishwasher pump assembly. More specifically, there exists a need for a pressure relief system that alleviates an over pressure condition in a filter chamber without increasing an overall noise output of the appliance.